MILEAGE PLAN MILEAGE PLAN (DETAILS) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Mileage Plan [Line Items]
Other accrued liabilities	$ 568		$ 557
Deferred revenue	441		443
Other liabilities	332		334
Total passenger revenue	978	896
Other - net	129	119
Total Operating Revenues	1,133	1,039
Liabilities From Mileage Plan [Member]
Mileage Plan [Line Items]
Other accrued liabilities	310		285
Deferred revenue	427		428
Other liabilities	16		17
Liabilities	753		730
Revenue From Mileage Plan [Member]
Mileage Plan [Line Items]
Total passenger revenue	46	43
Other - net	54	47
Total Operating Revenues	$ 100	$ 90